Typically, a wafer board panel comprises layers of wood flakes or wafers formed into a composite structure using a resinous binder. The preparation of wafer board panels is complex, but broadly consists of two principal stages. The first stage comprises the preparation of the wafers and the admixing thereof to form a loose layer or mat. The second stage involves subsequent compression and heating of the mat to cure the resin and form the consolidated panel.
Until recently, wafer board was manufactured in the form of planar or flat sheets. However, as disclosed in U.S. Pat. No. 4,616,991, the present applicant has developed an apparatus and process for the manufacture of panels having a wave-like or corrugated configuration. Such wave-board panels have improved structural strength properties, relative to planar panels.
This prior patented apparatus involved a pair of opposed, spaced-apart, upper and lower platens. Each platen was formed of adjacent lengths of chain-like links. When the lengths were pushed inwardly from the side, they would shift from a planar to an undulating corrugated form.
The process steps involved:
distributing a mat of loose wood wafers between the upper and lower platen surfaces while they were maintained in the planar configuration;
biasing the platens together to pre-compress the mat, and thereby substantially fixing the wafers together to limit their further relative movement;
converting the two platen surfaces, still in pressing association with the mat, from the planar to the corrugated configuration; and
then applying additional pressure and heat for a sufficient time to cure the binder and produce a corrugated sandwich wave-board panel.
The main advantage inherent in the patented process was that the panel product so formed was characterized by having a substantially uniform density. This was achieved because the wafers were fixed by the pre-compression step and because the mat was not significantly stretched or elongated during the conversion from the planar to the corrugated configuration.
It would be an advantage if one could provide a corrugated metal-clad sandwich panel. By metal clad is meant with a metal sheet cohesive with the wafer board core on at least one face thereof. The metal-clad panel would find use in high moisture-exposure applications (i.e. roof sheeting or the like).